The present invention relates to a device for allowing a recording to be made on a cassette without a recording tab.
Both video and compact cassettes (which are commonly used for recording music, but are finding increasing use for storing computer infomation, such as computer programs) can be purchased in either prerecorded or blank form. In the latter case, the cassette owner may record on the cassette material which he values, and may wish to protect against accidental erasure. To allow for this, blank video and compact cassettes include a protecting recess formed in one of their side edges, the opening of which is barred by a recording tab. The recording tab can be snapped off from the cassette housing thus exposing the protecting recess which prevents material being recorded on and erased from the cassette as explained below.
Video and audio cassette recorders include a mechanism for detecting whether or not a loaded cassette has a recording tab or not. This mechanism usually consists of a probe which is biased to extend into the protecting recess of the cassette housing (the extended position). However, if a recording tab is present, the probe is prevented from entering the recess, and instead abuts against the tab (the contracted position). The remaining parts of the mechanism sense which of these alternative positions the probe is in, and if it is found to be extended, prevent the recorder from recording on and erasing from the loaded cassette.
A protecting recess is also provided in the housings of pre-recorded cassettes, but without there being a recording tab.
After repeatedly viewing or listening to a prerecorded cassette, or to a recording made on a blank cassette which has been protected, the viewer or listener may become tired of it, and wish to record fresh material in its place. However, because the recording tab is absent, the detecting mechanism prevent the recorder from recording on or erasing material from the cassette as previously explained. Consequently, it is necessary to shield the protecting recess causing the probe to be in its contracted position when the cassette is loaded.
The problem therefore arises of how to satisfactorily shield the recess of a cassette.
Commonly this problem has been solved by attaching sticky tape across the entrance of the recess to mimic the recording tab. However, the sticky tape itself may get pierced where it passes over the recess by the probe of the recorder, or by accident thus rendering the sticky tape ineffective. Consequently, a fresh piece of sticky tape is required. Eventually, the cassette housing becomes unsightly and tacky around the recess and the cassette becomes unpleasant to handle.
In addition, once the sticky tape is attached to the cassette across the recess, it is difficult to peel off.
The use of a plug for blocking the recess of a cassette has been suggested previously. However the plugs hitherto known have been either difficult to remove from the recess once in place or fit so loosely that they easily become detached from the cassette and lost, possibly falling into the drive mechanism of the recorder causing it to break down. Consequently, their use has been dismissed as impractical by those skilled in the art as exemplified by lines 9-14, column 2, of U.S. Pat. No. 4,044,386 (TDK Electronics Co. Ltd.).